In recent years, together with the growth of information communication technology, technology is being developed in relation to augmented reality with which a computer is used to add visual information to an image in which a real space (external environment) has been captured, and to display the image. For the display of the visual information, for the most part, a wearable device such as a head-mounted display (HMD) having a camera that acquires an image of the external environment mounted thereon is used, and detailed information (hereafter referred to as an additional information image) relating to a recognition subject (in other words, subject recognized) that is present in the line of sight of the user is superimposed on the image of the external environment and displayed.
Augmented reality technology is used to realize a function that supports the designation of a fault location when a fault occurs in an electronic device or the like, and supports fault repair work carried out by the user. For example, Japanese Laid-open Patent Publication No. 2008-201101 discloses technology with which, in the support of repair work for a paper jam fault in a copy machine, an operation procedure and an internal image of the copy machine which constitute an additional information image and are prepared in advance in association with a paper jam occurrence location are superimposed and displayed on the copy machine which constitutes the recognition subject. In this technology, because the additional information image conceals the recognition subject, technology that avoids concealment caused by the superimposition and display of the additional information image is also disclosed. For example, Japanese Laid-open Patent Publication No. 2006-12042 discloses technology for switching between displaying or not displaying the superimposition of an additional information image by the operation of a physical mechanism (switch). In addition, Japanese Laid-open Patent Publication No. 2009-251154 discloses technology for estimating the work state of the user on the basis of the amount of oscillation of the head of the user calculated from images captured by a camera mounted on the head, and switching between displaying or not displaying the superimposition of an additional information image.